THIRD VENTRICULAR EPENDYMOMAS are rare tumors that have not been specifically examined. Four cases of these tumors are reported. The presenting symptoms included headache, ataxia, vertigo, and Parinaud's syndrome. All the patients underwent computed tomographic scanning and cerebral angiography, followed by craniotomy and microsurgical resection of the tumor. In addition, all patients had or developed symptomatic obstructive hydrocephalus requiring shunting procedures. Three of the patients are alive with a follow-up of 4 to 12 years. It is remarkable that these tumors are so rare, given that the ependymal surface area of the third ventricle is greater than that of the fourth. The management of these tumors should include aggressive surgical resection, radiation therapy, and cerebrospinal fluid diversion.